Internal combustion engine ignition system



Jan. 8, 1963 T. E. KIRK INTERNAL COMBUSTION ENGINE IGNITION SYSTEMINVENTOR.

THOMAS E. KIRK a RI MM HIS ATTORNEY Filed June 23, 1960 3,ti72,823TNTERNAL (IOMBUSTHON ENGINE TGNHTIGN SYSTEM Thomas E. Kirk, Anderson,Ind, assignor to General Motors Corporation, Detroit, Mich, acorporation of Delaware Fitted dune 23, 196i Ser. No. 38,204 12 Claims.(Cl. 315-205) This invention relates to an ignition system for aninternal combustion engine and more particularly to an ignition systemwherein a semi-conductor such as a transistor is used to control currentflow through the primary winding of an ignition coil.

One of the objects of this invention is to provide an ignition systemfor controlling the firing of a spark plug of an internal combustionengine that includes a pair of semi-conductors that are connected to bealternately conductive and wherein one of the semi-conductors isconnected to control the current fiow through the primary winding of anignition coil.

Another object of this invention is to provide an internal combustionignition system including a pair of interconnected transistors, one ofwhich controls current flow through the primary winding of an ignitioncoil and the other of which has its conductance controlled by a devicewhich operates in timed relationship to rotation of the crank shaft ofthe engine.

A further object of this invention is to provide an ignition system foran internal combustion engine that includes a first transistor thatcontrols current flow through the primary winding of an ignition coiland a second transistor connected with the first transistor, the secondtransistor being normally biased to a state of conduction and beingperiodically rendered non-conductive by a voltage pulse generatingdevice that operates in synchronism with the engine.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

FIGURE 1 is a schematic illustration of an ignition system made inaccordance with this invention.

FIGURE 2 illustrates a modified ignition system made in accordance withthis invention.

Referring now to FIGURE 1 the reference numeral designates a source ofdirect current power which in this case is a storage battery. Thestorage battery in the motor vehicle is connected to be charged by agenerator (not shown) and when the generator is in operation thegenerator does provide power for the ignition system. It is seen thatone side of the battery 10 is connected directly to ground whereas theopposite side thereof is connected with an ignition switch 12.

The ignition system includes an ignition coil generally designated byreference numeral 14 having a primary winding 16 and a secondary winding18. One side of the primary winding 16 is connected directly to groundas well as one side of the secondary winding 18. The opposite side ofsecondary winding 18 is connected with a rotor contact 20 of adistributor which cooperates with the contacts 22 carried by thedistributor cap 24. The contacts 22 are connected by suitable lead Wireswith spark plugs and, as is well known to those skilled in the art, asthe rotor 20 rotates, spark impulses are supplied to the spark plugs ofthe engine. In the schematic illustration only one spark plug 26 isshown, it being understood however, that each distributor cap contact isconnected with a spark plug. It will, of course, be appreciated that therotor 20 is driven in synchronism with the en- 3,072,823 Patented Jan.8, 1963 gine in a manner well known to those skilled in the art.

One side of the primary winding 16 of ignition coil 14 is connected withthe collector electrode 28 of a pnp transistor generally designated byreference numeral 30. This transistor has a base electrode 32 and anemitter electrode 34. The emitter electrode 34 is connected with thelead wire 36 which, in turn, is connected to one side of ignition switch12. The base electrode 32 of transistor 30 is connected with a junction38 and it is seen that resistor 40 is connected between lead wires 36and the base electrode of transistor 36 and, thus, is connected acrossthe emitter and base electrodes of transistor 30.

A second transistor generally designated by reference numeral 42 isprovided which has an emitter electrode 44, a base electrode 46, and acollector electrode 48. This transistor is also a pnp transistoralthough it will be apparent to those skilled in the art that npntransistors could be used for transistors 30 or 42. The emitterelectrode 44 of transistor 42 is connected directly with lead wire 36whereas the collector electrode 48 is connected with junction 38. Thejunction 38 is connected to ground through a resistor 50.

The device for causing a timed firing of the spark plugs in the ignitionsystem of this invention includes a voltage pulse generating devicehaving a pickup coil 52 and a permanent magnet rotor assembly 54. Thepermanent magnet assembly 54 is driven by a shaft 56. The shaft 56 isdriven in synchronism with the rotor contact 20 and both of theseelements are driven by the engine. The rotor assembly 54 will have sixpermanent magnets when used with a six cylinder engine so that as thepermanent magnet assembly 54 rotates with respect to pick up coil 52 sixpulses of voltage are generated in the pickup coil for every revolutionof the shaft 56. It is pointed out that the number of permanent magnetsincluded in the rotor assembly 54 forms no part of this invention and asmany magnets may be used as are required depending upon the number ofcylinders of the engine.

In the operation of the ignition system of FIGURE 1, when the ignitionswitch 12 is closed a circuit is completed to one side of the storagebattery 10. It will be observed that the emitter electrode 44 oftransistor 42 is at the same potential as one side of the battery it andfurther that the base electrode 46 of transistor 42 is substantially atthe same potential since it is connected with lead wire 36 through thepickup coil 52. It, thus, is seen that with the ignition switch 12closed the emitter and base electrodes of transistor 42 are atsubstantially the same potential so that the transistor 42 isnon-conductive between emitter and collector.

On the other hand, when the ignition switch 12 is closed, the transistor30 is biased to be fully conductive between emitter and collector sothat upon initial closing of the ignition switch current will flowthrough the primary winding 16 of the ignition coil. If the engine isnow cranked so that the shaft 56 and rotor contact 20 are rotated,pulses of voltage will be generated in the pickup coil 52 as thepermanent magnet assembly rotates with respect thereto. These pulses ofvoltage are of such a polarity as to cause the emitter electrode 44 oftransistor 42 to become positive with respect to the base electrode 46and thus cause the transistor 42 to become conductive between emitterand collector. With transistor secondary winding 18 which is applied tothe spark plugs 26 through the rotor contact 20. The same operationoccurs once the engine has been started since the rotor assembly 54causes pulses of voltage to be generated in the pickup coil 52 and thuscauses transistor 42 to be periodically turned on with a consequentperiodic shutting E of transistor 30.

It will be apparent from the foregoing that the transistor 42 isnormally non-conductive except when a pulse of voltage is induced in thepickup coil 52. It will also be apparent that the conduction oftransistor 30 is opposite to the state of conduction of transistor 42,or in other words, when transistor 42 is fully conducting, transistor 30is fully non-conductive and vice versa.

Referring now more particularly to FIGURE 2, a modified ignition systemmade in accordance with this invention is illustrated. In FIGURE 2 thesame reference numerals have been used as Were used in FIGURE 1 toidentify the same circuit element in each figure. The FIGURE 2arrangement illustrates an ignition system that is operable without theuse of breaker points, a distributor or a distributor cap.

In the FIGURE 2 arrangement a pair of ignition coils are employed, oneof which is designated by reference numeral 60 and the other of which isdesignated by reference numeral 62. The ignition coil 60 has a primarywinding 64 and a secondary winding 66. In a like manner, the ignitioncoil 62 has a primary winding 68 and a secondary winding 70. It is seenthat the secondary winding 66 is connected directly with spark plugs 71and 72 whereas the secondary winding 70 is connected directly with sparkplugs 76 and 78.

In the embodiment of FIGURE 2 a magnetic rotor assembly 80 is providedhaving four permanent magnets and this rotor assembly is rotatablydriven by a shaft 82. It will, of course, be appreciated that themagnetic rotor 30 might be affixed directly to the fly wheel of anengine, it being understood that any arrangement may be employed whereina magnetic rotor assembly is rotated in timed relationship with theengine.

The rotor assembly 80, as it rotates, induces voltages in pickup coils84, 86, 88 and 90. The pickup coils 84 and 88 are used in starting theengine to provide a somewhat retarded spark. The pickup coils 86 and 90are, on the other hand, used when the engine is running and have anadvanced spark as compared to the situation where the coils 84 and 88are used. This being true, it is necessary, of course, that the coils 84and 83 be circumferentially spaced and, in a like manner, it isnecessary that coils 38 and 90 be circumferentially spaced so that apulse of voltage will be induced, for example, in coil 86 before one isinduced in coil 84 as the rotor member 80 rotates.

In the system of FIGURE 2 either the coils 84 and 88 are connected intothe circuit or the coils 86 and 90. This is accomplished by switchingmeans which includes movable contactors 92 and 94 which are gangedtogether and which cooperate respectively with contacts 96 and 98 andwith contacts 100 and 102. It is seen that the shiftable contactors 92and 94 are connected with the base electrodes of the transistors 42.

It can be seen from the FIGURE 2 embodiment that the ignition coils 60and 62 are fed through two different channels or circuits which areidentical with a part of the circuit illustrated in FIGURE 1. In otherwords, a pair of transistors 30 and 42 control the current flow to theprimary winding 64 of ignition coil 60 while still another pair oftransistors 30 and 42 control the current flow to the primary winding 68of ignition coil 62. It will be appreciated that when current flow isinterrupted to either primary winding 64 or 68, a spark impulse isapplied to spark plugs 71 and 72 or the spark plugs 76 and 7 8.

The pickup coils 84, 86, 88 and 90 are so spaced that the spark plugs 71and 72 will fire when, for example,

at the point of time where the piston within the cylinder that is firedby spark plug 71 is in the right point in its compression stroke. Itwill, of course, be appreciated that simultaneously with the firing ofspark plug 71 the spark plug 72 is likewise fired, but at that time, thepiston in the cylinder which is fired by spark plug 72 is in such aportion of its cycle that this firing has no harmful effect. The same istrue of the spark plugs 76 and 78 and it is, thus, seen that the fourcylinder engine will have properly timed sparking without the use of adistributor rotor, for example, like that illustrated by referencenumeral 20 in FIGURE 1.

As pointed out hereinbefore, when the engine is to be started thecontactor 92 is shifted into engagement with fixed contact 96 and thecontactor 94 is shifted into engagement with fixed contact 100. Thisbrings the pickup coils 84 and 88 into the circuit so that the spark issomewhat retarded during cranking or starting of the engine. On theother hand, once the engine is operating the contactors 92 and 94 may beshifted over into engagement with fixed contacts 98 and 102 to bring thepickup coils 86 and into operation whereby a slightly advanced sparkfrom that previously had is achieved.

In summary, it can be seen that the ignition system of FIGURE 2 providesproperly timed spark impulses to a four cylinder engine for firing thespark plugs of this engine wthout the use of breaker contacts or adistributor rotor and distributor cap. In addition, this control isachieved through the use of two circuit networks of transistors asexplained above.

While the embodiments of the present invention as herein disclosed,constitute preferred forms, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. An ignition system for controlling the firing of a spark plug in aninternal combustion engine comprising, a source of direct current power,an ignition coil having a primary winding and a secondary winding, meansconnecting said secondary winding with said spark plug. first and secondsemiconductors, means interconnecting said semiconductors and said powersource whereby said first semiconductor is substantially fullyconductive when the second semiconductor is substantially fullynon-conductive, means connecting said first semiconductor between saidpower source and the primary winding of said ignition coil, and meansfor controlling the conduction of said second semi-conductor in timedrelationship with operation of said engine.

2. An ignition system for controlling the firing of a spark plug in aninternal combustion engine comprising, a source of direct current power,an ignition coil having a primary winding and a secondary winding, meansconnecting said secondary winding with said spark plug, first and secondtransistors. means interconnecting said transistors and said powersource whereby one of said tran sistors is rendered substantially fullyconductive when the other of said transistors is substantially fullnon-conductive and vice-versa, means connecting one of said transistorsbetween said power source and the primary winding of said ignition coilwhereby the current flow through said primary winding is controlled as afunction of conductance of said one transistor, and means forcontrolling the conduction of said other transistor in timedrelationship to the operation of said engine.

3. An ignition system for controlling the firing of a spark plug in aninternal combustion engine comprising, an ignition coil having a primarywinding and a secondary winding, 21 direct current power source, meansconnecting the secondary winding of said ignition coil with said sparkplug, first and second transistors, means interconnecting saidtransistors and said power source whereby one of said transistors issubstantially fully conductive when the other of said transistors issubstantially fully non-conductive and vice-versa, means connecting oneof said transistors between said power source and the primary winding ofsaid ignition coil, a pulse generating device operative to supply pulsesof voltage in timed relationship with operation of said engine, andmeans for applying said pulses of voltage to the base circuit of saidother transistor.

4. An ignition system for controlling the firing of a spark plug of aninternal combustion engine comprising, a source of direct current power,an ignition coil having a primary winding and a secondary winding, meansconnecting said secondary winding with said spark plug,- semiconductormeans connected between said primary Winding and said power source forcontrolling the current flow through said primary winding as a functionof conductance of said semiconductor means, a pulse generating deviceincluding a pair of pickup coils and a magnetic device rotatable withsaid engine, and means for alternately connecting said pickup coils withsaid semiconductor means.

5. An electrical ignition system comprising, a source of direct currentpower, first and second ignition coils each having a primary winding anda secondary winding, first and second spark plugs, means directlyconnecting the secondary windings of said ignition coils respectivelywith said spark plugs, first semiconductor means connected with theprimary winding of one of said ignition coils, second semiconductormeans connected with the primary winding of the other ignition coil, andpulse generating means operated in synchronism with said engine forcontrolling the conduction of said semiconductor means.

6. An electrical ignition system comprising, a source of direct currentpower, first and second ignition coils each having a primary winding anda secondary winding, a first plurality of spark plugs directly connectedwith the secondary winding of said first ignition coil, a secondplurality of spark plugs directly connected with the secondary windingof said second ignition coil, first and second semiconductor meansconnected respectively between the power source and the primary windingsof said ignition coils, and pulse generating means operated insynchronism with said engine for controlling the conduction of saidsemiconductor means.

7. An ignition system for controlling the firing of spark plugs in aninternal combustion engine comprising, a first ignition coil having aprimary winding and a secondary winding, a second ignition coil having aprimary winding and a secondary winding, spark plugs directly connectedwith the secondary windings of said ignition coils, a source of directcurrent power, means for controlling the current flow between saidsource of power and the primary winding of said ignition coiis includingfirst and second semiconductor means, pulse generating means including amember rotatable with said engine and first and second pairs of pickupcoils, and means alternately connecting one of each of said pairs ofpickup coils in controlling relationship with one of said semiconductormeans.

8. An ignition system for controlling the firing of a spark plug of aninternal combustion engine comprismg, a source of unidirectionalvoltage, an ignition coil having a primary winding and a secondarywinding, means connecting said secondary winding with said spark plug,first and second transistors each having emitter, base and collectorelectrodes, an energizing circuit for the primary winding of saidignition coil including in a series connection, said voltage source,said primary winding and the emitter-collector circuit of said firsttransistor, means connecting the emitter-collector circuit of saidsecond transistor across said voltage source, a biasing circuit fornormally maintaining said first transistor conductive in itsemitter-collector circuit, said biasing circuit including in a seriesconnection, said voltage source and the emitter-base circuit of saidfirst transistor, means connecting the base electrode of said firsttransistor with the collector electrode of said second transistorwhereby said first transistor has its conductivity sub- 10. The systemaccording to claim 8 wherein the tim-' ing means includes a coil windingconnected across the emitter-base circuit of said second transistorwhich is capable of having voltage pulses induced therein in timedrelationship with operation of said engine.

11. An ignition system for controlling the firing of a spark plug in aninternal combustion engine comprising, a source of unidirectionalvoltage, an ignition coil having a primary winding and a secondarywinding, means connecting said secondary winding with said spark plug,first and second transistors each having emitter, base and collectorelectrodes, an energizing circuit for the primary winding of saidignition coil including in a series connection said source of voltage,said primary winding and the emitter-collector circuit of said firsttransistor, means connecting the collector electrode of said secondtransistor and the base electrode of said first transistor together andto one side of said source of voltage, means connecting the emitterelectrode of said second transistor to an opposite side of said voltagesource, a coil winding in which voltage pulses are induced in timedrelationship with operation of said engine, and means connecting saidcoil winding across the emitter and base electrodes of said secondtransistor, said coil winding being operative to place the emitter andbase electrodes of said second transistor at substantially equalpotentials when no voltage is induced in said coil winding and operativeto cause a difference in potential between said emiter and baseelectrodes when a voltage is induced in said coil winding.

12. An ignition system for controlling the firing of a spark plug in aninternal combustion engine comprising, a source of unidirectionalvoltage, an ignition coil having a primary winding and a secondarywinding, means connecting said secondary winding with said spark plug,first and second transistors each having emitter, base and collectorelectrodes, an energizing circuit for said primary winding including ina series connection, said source of voltage, said primary winding andthe emittercollector circuit of said first transistor, timing meansincluding a coil winding in which pulses of voltage are induced in timedrelationship with operation of said engine, means connecting one side ofsaid coil winding and the emitter electrode of said second transistorwith one side of said source of voltage, means connecting the oppositeside of said coil winding with the base electrode of said secondtransistor, means connecting the collector electrode of said secondtransistor with the side of said source of voltage opposite to thatwhich is connected with the emitter electrode of said second transistor,and a circuit connecting the collector electrode of said secondtransistor with the base electrode of said first transistor.

References Cited in the file of this patent UNITED STATES PATENTS1,272,056 Kettering July 9, 1918 1,676,503 Rippingille July 10, 19282,953,719 Guiot Sept. 20, 1960 3,034,018 Rosenberg May 8, 1962 FOREIGNPATENTS 1,137,949 France --.r-,- Jan. 21, 19 57

1. AN IGNITION SYSTEM FOR CONTROLLING THE FIRING OF A SPARK PLUG IN ANINTERNAL COMBUSTION ENGINE COMPRISING, A SOURCE OF DIRECT CURRENT POWER,AN IGNITION COIL HAVING A PRIMARY WINDING AND A SECONDARY WINDING, MEANSCONNECTING SAID SECONDARY WINDING WITH SAID SPARK PLUG, FIRST AND SECONDSEMICONDUCTORS, MEANS INTERCONNECTING SAID SEMICONDUCTORS AND SAID POWERSOURCE WHEREBY SAID FIRST SEMICONDUCTOR IS SUBSTANTIALLY FULLYCONDUCTIVE WHEN THE SECOND SEMICONDUCTOR IS SUBSTANTIALLY FULLYNON-CONDUCTIVE, MEANS CONNECTING SAID FIRST SEMICONDUCTOR BETWEEN